An anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units and a preparation method and application thereof

Abstract

The application belongs to the technical field of new material preparation, and discloses an anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units and a preparation method and application thereof. The preparation method of the novel anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units comprises the following specific steps: taking piperidone compounds and ethylene glycol as starting materials, piperidone hydrochloride is prepared into piperidone ketal under the action of an acid, then the 6,6-piperidone ketal spiro intermediate is generated by reacting with 1,5-dihalogenated alkane under the action of a base, and the anion exchange membrane is obtained by polymerizing with triphenyl and 2,2,2-trifluoroacetophenone under the action of an acid. The method prepares a novel anion exchange membrane containing short-chain 6,6-spirocyclic piperidine salt units, has simple operation, does not need precious metal catalyst, has less reaction equipment, has low cost, is easy to industrialize, and has good application prospect in the water electrolysis hydrogen production technology.

Description

Technical Field

[0001] This invention relates to the technical field of anion exchange membranes, specifically to an anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean and efficient renewable energy source, is receiving increasing attention worldwide and holds a crucial strategic position in the future energy structure transformation of nations. Electrolysis of water for hydrogen production has garnered widespread attention due to its ability to produce hydrogen efficiently and at low cost under mild conditions. Anion exchange membrane (AEM) water electrolysis has become a research hotspot in recent years, achieving both the economic efficiency of non-precious metal catalysts under alkaline conditions and the high energy efficiency of proton exchange membrane (PEM) water electrolysis systems. Anion exchange membranes (AEMs) are composed of polymers with covalently bound cation groups and free anions. As the core component of this technology, their main function is the selective transport of OH- ions while simultaneously blocking gases and reducing water migration, thus achieving high electrolysis efficiency and stability. Therefore, the design and synthesis of novel AEMs have been a focus of research.

[0003] Currently, the main core units for preparing AEM using publicly disclosed patented technologies include quaternary ammonium salts and imidazole salts, with the former being the primary component. While the nonpolar chain portions of quaternary ammonium salt AEMs in publicly disclosed patented technologies are diverse, their core ion-pair units are limited to a single-ring structure with a nitrogen atom at its core. For example, CN119447390A discloses a cross-linked polybenzimidazole anion exchange membrane and its preparation method, the ion pairs of which mainly consist of long-chain piperidine quaternary ammonium salts in the polybenzimidazole anion exchange membrane; CN120242762A discloses an AEM containing a long straight chain of dimethyl quaternary ammonium salt; CN119978274A discloses an AEM containing two ion pair units: dimethylcyclohexylamine salt and triethylenediamine salt; patents such as CN120082021A, CN116371478A, CN120665329A, CN119775540B, CN119775540A, CN117577908A, and CN 121222274A disclose an AEM containing a dimethylcyclohexylamine salt structure; CN 119039490A discloses an AEM containing a long-chain monosubstituted 6,6-spirocyclic piperidine salt doped with inorganic materials.

[0004] In summary, while innovation in AEM membranes continues, there has been very little innovation in the structure of the core unit of AEM, namely the cation-anion pair unit, and the focus is mainly on dialkyl non-spirocyclic substituted structures where stability needs improvement. The connection methods between the cation-anion structural units and the nonpolar main chain are also quite limited. Quaternary ammonium cations located at the benzyl position and on the ether bridge of the polymer main chain are particularly vulnerable to hydroxide ion attack, leading to cation loss and main chain breakage, respectively. The stability of AEMs with long-chain monosubstituted 6,6-spirocyclic piperidine salts needs improvement. Therefore, designing and synthesizing AEMs with novel cation-anion structures has always been a very active area of ​​innovation in this field, with the design and synthesis of corresponding monomers containing cation-anion pairs being the source of innovation. Summary of the Invention

[0005] To address the above technical problems, this invention provides an anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, its preparation method, and its applications. This invention provides a novel synthetic route for cation-anion pair units and uses it for the synthesis of corresponding AEM membranes. The innovation of this method lies in the development of a very practical synthetic monomer, the 6,6-spirocyclic piperidine quaternary ammonium salt unit, and its application in the direct di-substitution of a nonpolar backbone to synthesize anion exchange membranes containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units. The method for preparing the novel AEM disclosed in this invention is simple to operate, does not require expensive metal catalysts, and requires less reaction equipment, showing promising prospects for industrial production applications.

[0006] The first objective of this invention is to provide an anion exchange membrane comprising a short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound, the structural formula of which is shown below: Where Y is Br - or Cl - Or BF4, where m and n are natural numbers, m = 220 - 240, n = 180 - 220.

[0007] Furthermore, m can be any value from 220, 221, 223, 224, 225, 226, 227, 228, 229, 230, 231, 233, 234, 235, 236, 237, 238, 239, and 240, or any interval between any two values, such as 220~225, 220~230, and 230~240. n can be any value from 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, and 191, or any interval between any two values, such as 180~185, 180~190, 180~200, 180~210, and 180~220.

[0008] A second objective of this invention is to provide a method for preparing the aforementioned anion exchange membrane, comprising the following steps: A solution of a short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound is provided; After filtration through a filter membrane to remove insoluble substances, the membrane is then cast onto a substrate and dried to obtain a chloride ion membrane. The obtained chloride ion membrane is immersed in an alkaline solution to obtain the anion exchange membrane.

[0009] In some embodiments of the present invention, the substrate is selected from a glass plate or a polymer substrate.

[0010] In some embodiments of the present invention, the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound solution is prepared by the following method: S1. In the first reaction solvent, piperidone compounds react with ethylene glycol under the action of the first acid catalyst to obtain piperidone ketal; S2. In the second reaction solvent, piperidone ketal and 1,5-dihaloalkane react under the action of a base to generate a 6,6-piperidone ketal spirocyclic intermediate. S3. Under the action of the second acid catalyst, the 6,6-piperidine ketal spirocyclic intermediate, terphenyl, and 2,2,2-trifluoroacetophenone are polymerized in the third reaction solvent to obtain the solution of the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound.

[0011] In some embodiments of the present invention, in step S1, the mass ratio of the piperidone compound to ethylene glycol is 1:1-3; The first reaction solvent is tetrahydrofuran and / or toluene; The first acid catalyst is one or more of hydrochloric acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and diphenyl phosphate; The amount of the first acid catalyst used is 5-15 mol%; The reaction temperature is 100-120℃, and the reaction time is 4-8h.

[0012] In some embodiments of the present invention, in step S2, the 1,5-dihaloalkane includes 1,5-dichloropentane and / or 1,5-dibromopentane, and the amount of the 1,5-dihaloalkane is 1-1.5 equivalents; the base includes one or more of sodium bicarbonate, sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, and diisopropylethylamine; the amount of the base is 2-2.2 equivalents; the second reaction solvent is selected from one or more of tetrahydrofuran, methanol, ethanol, acetone, dichloromethyl sulfone (DMSO), and water; the reaction temperature is 60-100°C, and the reaction time is 10-20 h.

[0013] In some embodiments of the present invention, in step S3, the mass ratio of 6,6-piperidine ketal spirocyclic intermediate to terphenyl and 2,2,2-trifluoroacetophenone is 2:2:(0.3-1.0). The second acid catalyst includes one or more of trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and tetrafluoroboric acid; the amount of the second acid catalyst is 10-30 mol.

[0014] In some embodiments of the present invention, the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound is prepared by the following method: Piperidinone compounds, terphenyl, and 2,2,2-trifluoroacetophenone were dissolved in the first reaction solvent, mixed, and stirred in an ice bath. Then, an acid catalyst was added and the mixture was carried out at room temperature for 6-16 hours. The reaction solution was then separated into solid and liquid phases to obtain the first compound. 1,5-Dihaloalkanes and bases are added to the second reaction solvent and heated. The solution of the first compound is then added and reacted at a constant temperature for 4-8 hours. The solid phase is obtained by solid-liquid separation, and the obtained solid phase is the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound.

[0015] In some embodiments of the present invention, the molar ratio of piperidone compounds, terphenyl and 2,2,2-trifluoroacetophenone is 2:2:(0.3-1). The solvent for the first reaction is tetrahydrofuran and / or toluene; The acid catalyst is one or more of hydrochloric acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and diphenyl phosphate; The amount of the acid catalyst used is 5-15 mol.

[0016] In some embodiments of the present invention, the heating temperature is 60-80°C; 1,5-Dihaloalkanes include 1,5-dichloropentane and / or 1,5-dibromopentane. The amount of the 1,5-dihaloalkane used is 1-1.5 equivalents; The alkali includes one or more of sodium bicarbonate, sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, and diisopropylethylamine; The amount of alkali used is 2-2.2 equivalents; The second reaction solvent is selected from one or more of tetrahydrofuran, methanol, ethanol, acetone, dichloromethyl sulfone (DMSO), and water.

[0017] A third objective of this invention is to provide the application of the anion exchange membrane in hydrogen production via water electrolysis.

[0018] The beneficial effects of this invention are: (1) The present invention uses piperidone, ethylene glycol, terphenyl, and 2,2,2-trifluoroacetophenone as raw materials and prepares an AEM containing a short-chain 6,6-spirocyclic piperidinium quaternary ammonium salt unit through a three-step reaction under acid-base-acid catalysis. (2) In the AEM of the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt unit prepared by the present invention, the 6,6-spirocyclic piperidine quaternary ammonium salt unit directly and the nonpolar main chain form quaternary carbon center linkages through disubstitution; (3) The 6,6-spirocyclic piperidinone intermediate synthesized in this invention is a novel quaternary ammonium salt compound, which provides a new material basis for the development of novel AEMs; (4) The preparation method provided by the present invention does not require any precious metal catalysts, the reaction conditions are mild, there is no high temperature and high pressure, and the equipment requirements are low; it meets the requirements of green chemistry and sustainable development and has good prospects for industrial application. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is the synthetic route for the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt unit AEM prepared in this invention; Figure 2 This is a photograph of the AEM product of the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt unit prepared in Example 1 of this invention.

[0020] Figure 3 The graph shows the electrochemical performance and operational stability results of the electrolyzer in the examples at an operating temperature of 60°C. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] The general reaction route formula for the anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units in the embodiments of the present invention is as follows: , In the general structural formula, X = Cl, Br, Y = Cl, Br, BF4, m and n are natural numbers, m = 220-240, n = 180-220.

[0023] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0024] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0025] Example 1

[0026] This embodiment provides a method for preparing anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, as detailed below: I. Preparation of piperidine spirocyclic quaternary ammonium salt intermediate, the synthetic route is as follows:

[0027] 1. Under a nitrogen atmosphere, weigh 13.5 g (10 mmol) of piperidinone hydrochloride and 9.3 g (15 mmol) of ethylene glycol and place them in a round-bottom reaction flask equipped with a stir bar. Add 50 mL of toluene to dissolve the raw material, then add 0.17 g of p-toluenesulfonic acid (1 mmol, 10%). Stir at 100 °C and react for 4 h. Then remove the solvent by rotary evaporation and dry to obtain a white solid as the piperidinone ketal intermediate.

[0028] 2. Weigh 3.6 g of piperidine ketal intermediate and 4.2 g of 1.5 equivalents of 1,5-dichloropentane, dissolve in 25 mL of ethanol / water (v / v = 2:1), then add 1.7 g of 2.0 equivalents of NaHCO3, and react at 60 °C for 15 h. Remove the solvent by vacuum distillation, then add 15 mL of methanol to the reaction flask, stir, filter to remove the precipitate, and then remove most of the methanol by rotary evaporation under reduced pressure. After standing at room temperature, a white precipitate is obtained, and 4.84 g of white piperidine ketal spirocyclic ammonium chloride compound is obtained by filtration. (Yield 98%). NMR characterization data: 1 H NMR (400 MHz, DMSO-d6) δ 3.94 (s, 4H), 3.55 -3.43 (m, 8H), 1.96 - 1.88 (m, 4H), 1.79 - 1.68 (m, 4H), 1.58 - 1.48 (m, 2H)ppm; 13 C NMR (101 MHz, DMSO-d6) δ 104.3, 64.6, 58.4, 57.0, 29.0, 21.6, 19.6 ppm.

[0029] II. The preparation process of AEM membrane is as follows: Examples using piperidinone ketal spirocyclic quaternary ammonium chloride compounds as starting materials: , In a 10 mL round-bottom flask, piperidinone ketal spirocyclic quaternary ammonium chloride compound (496 mg, 2.0 mmol), terphenyl (460 mg, 2.0 mmol), and 2,2,2-trifluoroacetophenone (52 mg, 0.3 mmol) were added separately, along with ethanol (2.0 mL) and a magnetic stirrer. The mixture was stirred at room temperature for 10 minutes, and then 30 wt% trifluoromethanesulfonic acid was slowly added. The reaction was carried out at room temperature for 12 hours to obtain a viscous ionic polymer solution. The resulting ionic polymer solution was filtered through a 25 μm filter membrane, cast onto a glass plate, and then dried in a hot air oven at 80 °C for 24 hours to obtain a chloride ion membrane. After the membrane cooled to room temperature, it was immersed in deionized water and peeled off from the glass plate. The chloride ions (Cl...) were then... - A membrane in the form of a chloride ion is immersed in a 1 mol / L NaOH solution to further transfer negative ions from chloride ions (Cl... - The salts are exchanged for hydroxide ions (Y = OH in the equation). After thoroughly rinsing with deionized water to remove residual salts, the resulting hydroxide ions (HO) are... - The membrane, in the form of a 30-35 micrometer membrane, was stored at room temperature until use. NMR characterization data were... 1 ¹H NMR (400 MHz, DMSO-d⁶) δ 7.87 - 7.63 (m, 9H), 7.63 - 7.42 (m, 5H), 7.33 - 7.10 (m, 1H), 3.44 (s, 4H), 3.14 (s, 4H), 2.83 (s, 4H), 1.76 (s, 4H), 1.57 (s, 2H) ppm. The obtained hydroxide ions (HO₂) - The average molecular weight of the membrane in this form is 360482, the PDI is 1.23, m=230, and n=190.

[0030] Example 2

[0031] This embodiment provides a method for preparing anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, as detailed below: Preparation of other quaternary ammonium salt intermediates: This spiroketal piperidine quaternary ammonium chloride can be used directly to prepare AEM membranes, or the ketone protecting group can be removed under acidic conditions to obtain the piperone quaternary ammonium salt, which can then be used for AEM preparation. The reaction is as follows: , The reaction process is as follows: 0.8 g of piperidinone ketal spirocyclic quaternary ammonium chloride compound was dissolved in 2 mL MeOH / H2O (v / v = 4 / 3), and 10% trifluoroacetic acid was added. The mixture was stirred at room temperature for 30 min, and then the solvent was removed to obtain the quantitative target product of 6,6-spirocyclic piperidinone quaternary ammonium chloride. The analytical data are as follows: 1 ¹H NMR (400 MHz, DMSO-d⁶) δ 3.82 (t, J = 6.5 Hz, 4H), 3.64 - 3.55 (m, 4H), 2.70 (t, J = 6.4 Hz, 4H), 1.89 - 1.79 (m, 4H), 1.66 - 1.55 (m, 2H) ppm. Replacing trifluoroacetic acid with any of methanesulfonic acid, trifluoromethanesulfonic acid, or p-toluenesulfonic acid does not affect the yield of the target product (95-99%) or the purity of the product.

[0032] The preparation process of the AEM membrane was the same as in Example 1, except that spiroketone piperidinium chloride quaternary ammonium salt was replaced with an equimolar mass of 6,6-spirocyclic piperidinone quaternary ammonium chloride, and 10% trifluoroacetic acid was used to obtain chlorinated AEM. The resulting membrane had an average molecular weight of 348,760, a PDI of 1.20, m=224, and n=209. The reaction equation is as follows: .

[0033] Example 3

[0034] This embodiment provides a method for preparing anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, as detailed below: The synthesis of the brominated analog intermediate is as follows: The 4.2 g of 1,5-dichloropentane in Example 1 was replaced with 4.56 g (1 equivalent) of 1,5-dibromopentane, and the reaction temperature for preparing the spirocyclic compound was changed to 100°C, yielding a white piperidinone ketal spirocyclic quaternary ammonium bromide compound. 5.64 g (96%). NMR characterization data: 1 H NMR (400 MHz, DMSO-d6) δ 3.95 (s, 4H), 3.56 -3.44 (m, 8H), 1.95 - 1.85 (m, 4H), 1.80 - 1.67 (m, 4H), 1.60 - 1.50 (m, 2H)ppm; 13 C NMR (101 MHz, DMSO-d6) δ 104.4, 64.9, 58.5, 57.3, 29.1, 21.4, 19.7 ppm.

[0035] The preparation process of the AEM membrane is the same as in Example 1, except that the spiroketoperidine quaternary ammonium chloride salt is replaced with an equimolar mass of spiroketoperidine quaternary ammonium bromide salt, and 20% methanesulfonic acid is used as a catalyst to obtain brominated AEM. The average molecular weight is 358640, PDI=1.28, m=228, n=193. The equation is as follows: , Example 4

[0036] This embodiment provides a method for preparing anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, as detailed below: The carbonyl-deprotected spirocyclic bromide quaternary ammonium salt analog intermediate was synthesized as follows: Under the same reaction conditions as in Example 2, using EtOH / H2O (v / v=4 / 3) as solvent and 10-30% p-toluenesulfonic acid as catalyst, the decarbonylated 6,6-spirocyclic piperidinone quaternary ammonium bromide was obtained in 99% yield. NMR characterization data are 1 H NMR (400 MHz, DMSO-d6) δ 3.84 (t, J = 6.5 Hz, 4H), 3.66 - 3.54 (m,4H), 2.73 (t, J = 6.4 Hz, 4H), 1.90 - 1.77 (m, 4H), 1.65 - 1.50 (m, 2H) ppm.

[0037] The preparation process of the AEM membrane is the same as in Example 1, except that the spiroketoperidine quaternary ammonium chloride salt is replaced with an equimolar mass of spiroketoperidine quaternary ammonium bromide salt, and 20% methanesulfonic acid is used as a catalyst to obtain brominated AEM with an average molecular weight of 360910, PDI=1.32, m=229, and n=194. The equation is as follows: .

[0038] Example 5

[0039] This embodiment provides a method for preparing anion exchange membrane containing short-chain 6,6-spirocyclic piperidine quaternary ammonium salt units, as detailed below: The synthesis of tetrafluoroboronic acid analog intermediates is as follows:

[0040] 0.8 g of 6,6-spirocyclic piperidinone quaternary ammonium chloride was dissolved in ethanol, and an equivalent amount of 40% HBF4 aqueous solution was added. The reaction was carried out at 60°C for 30 min, and then the reaction solvent was removed by rotary evaporation to obtain a quantitative tetrafluoroborate product. Its NMR characterization data were as follows: 1H NMR (400 MHz, DMSO-d6) δ 3.77 (t, J = 6.5 Hz, 4H), 3.61 - 3.50 (m, 4H), 2.69 (t, J = 6.5 Hz, 4H), 1.89 - 1.78 (m, 4H), 1.66 - 1.51 (m, 2H) ppm; 13C NMR (101 MHz, DMSO-d6) δ 202.6, 58.9, 56.8, 34.8, 21.5, 19.7 ppm; 19F NMR (376 MHz, DMSO-d6) δ -148.20, -148.26 ppm The preparation process of the AEM membrane is the same as that in Example 1, except that the spirokepiperidine quaternary ammonium chloride salt is replaced with an equimolar mass of spirokepiperidine tetrafluoroborate quaternary ammonium salt, and 20% methanesulfonic acid is used as a catalyst to obtain tetrafluoroborate AEM with an average molecular weight of 361210, PDI=1.38, m=230, and n=191. The equation is as follows: .

[0041] Example 6

[0042] This embodiment provides a one-pot method for synthesizing AEM membranes, as detailed below: .

[0043] In a 10 mL round-bottom flask, piperidinone (200 mg, 2.0 mmol), terphenyl (460 mg, 2.0 mmol), and 2,2,2-trifluoroacetophenone (52 mg, 0.3 mmol) were added, along with 2.0 mL of toluene solvent, and the flask was equipped with a magnetic stirrer. The mixture was stirred in an ice bath for 10 minutes. Then, 15% trifluoromethanesulfonic acid and an equivalent of hydrochloric acid were slowly added. The reaction was carried out at room temperature for 8 hours to obtain a viscous solution. This solution was added to ethanol / water (150 mL, V / V = 1 / 1) to precipitate, and the white powder was filtered and dried to obtain M-1 (96%). Its NMR characterization data are as follows: 1¹H NMR (400 MHz, DMSO-d⁶) δ 8.38 (s, 2H), 7.87 - 7.68 (m, 9H), 7.61 - 7.44 (m, 5H), 7.26 - 7.11 (m, 1H), 3.11 (s, 4H), 2.68 (s, 4H) ppm. 1,5-Dichloropentane (1.68 g, 12 mmol) and diisopropylethylamine (8.8 mL, 50 mmol) were added to DMSO (10 mL) and heated to 60 °C. A DMSO solution of M-1 was added dropwise to the reaction system with stirring, maintaining the reaction temperature and continuing stirring for 16 h. After the reaction was complete, the mixture was added to an aqueous potassium carbonate solution (100 mL) for redeposition. The precipitate was collected by filtration, and the white solid was dried under vacuum at 80 °C for 12 h to prepare M-2, with a yield of 93%. The average molecular weight of the brominated AEM membrane M-2 is 352760, PDI=1.33, m=225, n=189.

[0044] Example 7

[0045] Following the preparation method of Example 6, in the second step of the reaction, 1,5-dichloropentane was replaced with an equivalent amount of 1,5-dibromopentane, and diisopropylethylamine was replaced with an equivalent amount of sodium hydroxide to obtain M-2 in the same manner.

[0046] Example 8

[0047] Following the preparation method of Example 6, in the second step of the reaction, 1,5-dichloropentane was replaced with an equivalent amount of 1,5-dibromopentane, and diisopropylethylamine was replaced with an equivalent amount of sodium carbonate. M-2 could be obtained in the same manner.

[0048] Example 9

[0049] Following the preparation method of Example 6, in the second step of the reaction, 1,5-dichloropentane was replaced with an equivalent amount of 1,5-dibromopentane, and diisopropylethylamine was replaced with an equivalent amount of potassium carbonate. M-2 could be obtained in the same manner.

[0050] Example 10

[0051] Following the preparation method of Example 6, in the second step of the reaction, 1,5-dichloropentane was replaced with an equivalent amount of 1,5-dibromopentane, and diisopropylethylamine was replaced with an equivalent amount of potassium hydroxide. M-2 could be obtained in the same manner.

[0052] Membrane performance testing 1. Mechanical performance testing The mechanical testing method was in accordance with the national standard GB / T 20042.3. The hydroxide AEM membrane prepared in Example 1 was tested five times, and the average tensile strength was 61 MPa.

[0053] 2. Water absorption and swelling test The hydroxide AEM membrane prepared in Example 1 was cut into three standard membranes of 1cm*1cm size. Each membrane was placed in 1 MKOH solution with the alkali changed three times. The swelling performance was tested in deionized water at 80℃. The results showed that the average swelling rate of the hydroxide AEM membrane prepared in Example 1 was 4.6%. 3. OH- ion conductivity performance test The hydroxide AEM membrane prepared in Example 1 was immersed in 1 M KOH solution, and its ionic conductivity was 141 mS / cm at 80°C; after immersion for 1000 h, the ionic conductivity decreased by only 2.3%.

[0054] 4. Electrolytic cell voltage and stability test: like Figure 3 As shown in Figure a, an electrolytic cell was assembled using the hydroxide AEM membrane prepared in Example 1 and commercial Pt / C as the cathode and NiFe-LDH as the anode. 1 M KOH was used as the electrolyte, and the catalyst had a geometric area of ​​1 cm². 2 The experimental system maintained a precise temperature of 60°C using a thermostat and a constant-temperature oil bath, with a peristaltic pump ensuring electrolyte circulation at a flow rate of 60 rpm. All electrochemical tests were performed using a Xinwei eight-channel electrochemical workstation. The electrolytic cell was activated before testing at a scan rate of 20 mV / s within a voltage range of 1.4–2.4 V. Figure 3 As shown in Figure b, the electrolyzer exhibits excellent electrochemical performance and operational stability at an operating temperature of 60°C. At 500 mA cm⁻¹ -2 At high current densities, the cell voltage is only 1.7 V, indicating low electrochemical polarization and good reaction kinetics. More notably, as... Figure 3 The electrolytic cell shown in C can operate stably for more than 70 hours under this high current condition without significant performance degradation, demonstrating the good durability of the material and membrane electrode structure during long-term operation.

[0055] These performance results demonstrate that the hydroxide AEM membrane prepared in Example 1 has significant stability and conductivity, and has certain commercial application potential in water electrolysis applications.

[0056] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. An anion exchange membrane, characterized in that, Including short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compounds, with the following structural formula: Where Y is Br - or Cl - Or BF4, where m and n are natural numbers, m = 220 - 240, n = 180 - 220.

2. The method for preparing the anion exchange membrane according to claim 1, characterized in that, Includes the following steps: A solution of a short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound is provided; After filtration through a filter membrane to remove insoluble substances, the membrane is then cast onto a substrate and dried to obtain a chloride ion membrane. The obtained chloride ion membrane is immersed in an alkaline solution to obtain the anion exchange membrane.

3. The method for preparing the anion exchange membrane according to claim 2, characterized in that, The short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound solution was prepared by the following method: S1. In the first reaction solvent, piperidone compounds react with ethylene glycol under the action of the first acid catalyst to obtain piperidone ketal; S2. In the second reaction solvent, piperidone ketal and 1,5-dihaloalkane react under the action of a base to generate a 6,6-piperidone ketal spirocyclic intermediate. S3. Under the action of the second acid catalyst, the 6,6-piperidine ketal spirocyclic intermediate, terphenyl, and 2,2,2-trifluoroacetophenone are polymerized in the third reaction solvent to obtain the solution of the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound.

4. The preparation method according to claim 3, characterized in that, In step S1, the mass ratio of the piperidone compound to ethylene glycol is 1:1-3; The first reaction solvent is tetrahydrofuran and / or toluene; The first acid catalyst is one or more of hydrochloric acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and diphenyl phosphate; The amount of the first acid catalyst used is 5-15 mol%; The reaction temperature is 100-120℃, and the reaction time is 4-8h.

5. The preparation method according to claim 3, characterized in that, In step S2, the 1,5-dihaloalkane includes 1,5-dichloropentane and / or 1,5-dibromopentane, and the amount of the 1,5-dihaloalkane used is 1-1.5 equivalents; the base includes one or more of sodium bicarbonate, sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, and diisopropylethylamine; the amount of the base used is 2-2.2 equivalents; the second reaction solvent is selected from one or more of tetrahydrofuran, methanol, ethanol, acetone, dichloromethyl sulfone (DMSO), and water; the reaction temperature is 60-100℃, and the reaction time is 10-20 h.

6. The preparation method according to claim 3, characterized in that, In step S3, the mass ratio of 6,6-piperidine ketal spirocyclic intermediate to terphenyl and 2,2,2-trifluoroacetophenone is 2:2:(0.3-1.0). The second acid catalyst includes one or more of trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and tetrafluoroboric acid; the amount of the second acid catalyst is 10-30 mol.

7. The method for preparing the anion exchange membrane according to claim 2, characterized in that, The short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound was prepared by the following method: Piperidinone compounds, terphenyl, and 2,2,2-trifluoroacetophenone were dissolved in the first reaction solvent, mixed, and stirred in an ice bath. Then, an acid catalyst was added and the mixture was carried out at room temperature for 6-16 hours. The reaction solution was then separated into solid and liquid phases to obtain the first compound. 1,5-Dihaloalkanes and bases are added to the second reaction solvent and heated. The solution of the first compound is then added and reacted at a constant temperature for 4-8 hours. The solid phase is obtained by solid-liquid separation, and the obtained solid phase is the short-chain 6,6-spirocyclic piperidine quaternary ammonium salt compound.

8. The method for preparing the anion exchange membrane according to claim 7, characterized in that, The molar ratio of piperidone compounds, terphenyl, and 2,2,2-trifluoroacetophenone is 2:2:(0.3-1). The solvent for the first reaction is tetrahydrofuran and / or toluene; The acid catalyst is one or more of hydrochloric acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, and diphenyl phosphate; The amount of the acid catalyst used is 5-15 mol.

9. The method for preparing the anion exchange membrane according to claim 7, characterized in that, Heating temperature: 60-80℃; 1,5-Dihaloalkanes include 1,5-dichloropentane and / or 1,5-dibromopentane. The amount of the 1,5-dihaloalkane used is 1-1.5 equivalents; The alkali includes one or more of sodium bicarbonate, sodium hydroxide, sodium carbonate, potassium carbonate, potassium hydroxide, and diisopropylethylamine; The amount of alkali used is 2-2.2 equivalents; The second reaction solvent is selected from one or more of tetrahydrofuran, methanol, ethanol, acetone, dichloromethyl sulfone (DMSO), and water.

10. The application of the anion exchange membrane described in claim 1 in hydrogen production by water electrolysis.

Images